Answer:
Step-by-step explanation:
Firstly, let’s define the common difference of an arithmetic sequence :
it’s the real number that we add to a term of the sequence to get the next term.
→ (-20)-(-11)=-9 ,here we added (-9) to (-11) to get (-20)
→ (-29)-(-20)=-9 ,here we added (-9) to (-20) to get (-29)
conclusion: the common differenc is -9
